Acadia's PWS Candidate Failure Leaves Soleno Unchallenged in Hyperphagia Market

Acadia Pharmaceuticals' phase 3 trial for its intranasal carbetocin treatment for hyperphagia in Prader-Willi Syndrome (PWS) has failed to meet its primary endpoint, leading the company to discontinue further development of the candidate. This setback leaves Soleno Therapeutics as the sole player in the market for hyperphagia treatments associated with PWS.

Trial Failure and Market Implications

The phase 3 trial, which enrolled 175 children and adults aged 5 to 30 with PWS, aimed to demonstrate a statistically significant improvement on the Hyperphagia Questionnaire for Clinical Trials (HQ-CT) over placebo after 12 weeks of treatment. Participants in the treatment group received three 3.2-mg doses of intranasal carbetocin daily. However, the study failed to achieve its primary endpoint, prompting Acadia to abandon further investigation of the candidate.

This development has had immediate market repercussions, with Soleno Therapeutics' share price increasing by 11% following the announcement, while Acadia's stock tumbled by 9%. The failure of Acadia's candidate solidifies Soleno's position as the only company marketing a treatment for hyperphagia in PWS patients.

Soleno's Market Dominance with Vykat XR

Soleno Therapeutics has been experiencing significant success with its FDA-approved treatment, Vykat XR, since its launch in March. The once-daily, extended-release tablet, priced at $466,200 annually, generated $33 million in sales during the second quarter alone. As a potassium channel activator, Vykat XR offers a unique mechanism of action for managing the insatiable hunger that characterizes PWS.

The failure of Acadia's candidate, which aimed to provide an alternative treatment option with a different mechanism of action, further cements Soleno's market position. PWS patients, who often require constant supervision to prevent overeating, will continue to rely on Vykat XR as the primary pharmaceutical intervention for hyperphagia management.

Acadia's Future Plans and Pipeline

Despite this setback, Acadia Pharmaceuticals remains optimistic about its future prospects. CEO Catherine Owen Adams emphasized that the company is well-positioned for long-term, sustainable growth, with two approved products expected to generate over $1 billion in revenue this year.

Looking ahead, Acadia plans to initiate seven phase 2 or phase 3 trials next year, with four data readouts anticipated by the end of 2027. The company's R&D chief, Elizabeth Thompson, Ph.D., stated that while they will not pursue further investigations of intranasal carbetocin, they remain committed to sharing a summary of the trial data to benefit the PWS community.

Acadia's decision to discontinue the development of intranasal carbetocin marks the end of a journey that began with its $10 million acquisition of the candidate from Levo Therapeutics in 2022. Despite the previous failure in a phase 3 study, Acadia had hoped to succeed by employing a smaller dose over a longer treatment period.

As the pharmaceutical landscape for PWS treatments continues to evolve, the industry will be watching closely to see how Soleno capitalizes on its market dominance and whether new challengers will emerge to address the unmet needs of patients with this rare genetic disorder.